The present invention relates to a structure and method of installing a photovoltaic module on a roof, etc., at a given location such as on the roof of a building.
A photovoltaic module is known as one way for obtaining electric energy. The photovoltaic module is often installed at a location well exposed to solar energy, such as the roof of a building.
There are two type of photovoltaic modules--a crystalline type and an amorphous type. In one practical form of a thin film amorphous type, transparent conductive films are formed at predetermined intervals in a band-like fashion on one-side (back surface side) of a glass substrate.
A plurality of band-like cells are arranged at predetermined intervals on the transparent conductive film and formed of a semiconductor layer. A back electrode layer is formed on each cell in a stacking fashion. The respective adjacent cells are electrically connected, in a serial array, through the transparent conductive film and back electrode layer.
Bus bars, as output power collecting electrodes, are attached to the transparent conductive films at one end and at the other end. One of the bus bars serves as an anode and the other bus bar serves as a cathode.
The cells formed on the back surface side of the glass substrate are sealed with resin and the resin is covered with a resin film. The longitudinal end sides of the paired bus bars extend through the resin and a power output of the solar cells is obtained across these bus bars.
In the photovoltaic module thus configured, the sealing of the resin at the back side of the glass substrate is achieved by joining a sheet-like resin to the back side, setting the joined area under reduced pressure and further heating the resin.
If any external force is inadvertently applied to the resin and bus bars when the photovoltaic modules are installed or, for example, after such installation is done, then the seal quality by the resin sometimes deteriorates.
In the case where a photovoltaic module with a deteriorated resin-sealing quality is placed on the roof of a building, etc., there is sometimes the case that rainwater seeps into the module and causes corrosion in the photovoltaic module.